Drilling fluids in the oil and gas industries perform a myriad of tasks, including cleaning wells, holding cuttings in suspension, reducing friction, lubricating drilling tools, maintaining stability of wellbores, and preventing fluid loss. The drilling fluids must be viscous to suspend cuttings in the fluid, and must have control of this viscosity over a broad temperature range, as oil and gas wells can be located in a multitude of diverse locations, for example, conditions of from less than 0° C. in freezing permafrost zones to temperatures exceeding 400° C. in geothermal wells.
Surfactants can be added to fluids as rheology modifiers to ensure performance of these tasks. A surfactant refers to a compound that reduces the surface tension or interfacial tension between two or more liquids or between a liquid and a solid. Surfactants may provide improved performance, including rheological performance, as additives in various fluids, such as drilling fluids, cleaning solutions, paints and coatings, corrosion inhibitors, and personal care formulations. Conventional surfactants include dimer diamines, dimer diacids, and esters of dimer acids. However, these compounds do not perform well over a broad temperature range and are difficult to synthesize.